1. Field of the Invention
This invention relates generally to the internal mounting mechanism of an electronic enclosure system, e.g., a portable computer, and more particularly, to an enclosure system comprising one or more electronic modules and an external enclosure case for mounting all these module assemblies without screws.
2. Description of the Prior Art
The internal mounting mechanism design of portable computers is becoming more and more challenging and difficult as portable computers become smaller and lighter. Electronic and hard tooling designs are complicated by different system form factors, such as laptop, notebook, sub-notebook, and palmtop. Any change in a portable computer's external industrial design or internal mounting design always results in significant costs and engineering effort, as well as associated incompatibility and obsolescence problems between old and new products. However, severe market competition and ever-changing customers' demands and tastes give portable computer vendors no choice. Constant changes in mechanical or electronic designs are part of the daily events faced by portable computer vendors. At the same time, the fast progress in computer technology, with its ever-decreasing sizes has made the internal mounting problems more complex. New progress is made daily in many areas such as small hard drives, pen-based computing, wireless communication, multimedia, etc. Severe price competition, plus lack of expandability, makes it a tricky task for portable computer vendors to decide whether to integrate a new component or not. Most of the problems experienced in portable computers are caused by the systems' overly complicated internal mounting mechanism designs.
The traditional screw mounting mechanisms of desktop computers used for the mounting of internal modules conform to several established component form factor standards for add-on cards, drives, power supplies, or motherboards, etc. The system of desktop standards is bulky but works. The great expandability and wide range of commercially available standard modules is one of the major reasons that personal computers are so popular. But unfortunately this story has not been duplicated in the current generation of portable computers. In mounting so many small components in a portable computer case, screw mounting mechanisms lose their traditional advantages. Highly integrated PCB boards designed to fit small, irregular spaces make a portable computer more compact also make it difficult to accommodate new design changes. Small precision screws used to support PCB boards and modules not only make it difficult to change the hard tooling, but also make it difficult to work with the computers. Some portable computers sold in current markets have more than 30 screws inside. It is not easy to assemble or maintain systems like these. Additionally, the sophisticated internal mounting mechanism supported by screws and fixed frames makes a portable computer weak in terms of shock protection. Shocks such as dropping a portable computer on the ground often cause severe damage to internal components and their sophisticated mounting mechanisms. The rigid screw mounting also provides no protection from vibrations either from inside the system like the noise from a hard drive, or from outside the system like vibration from a factory floor or car.
In addition to all these drawbacks, screw mounting is also a key obstacle in portable computer modularization. Small drive form factors including 3.5", 2.5", 1.8" and 1.3" are often defined based on screw mounting requirements. The hard tooling changes and incompatibilities between different form factors make it difficult for system vendors to choose to implement new technology, and also make component vendors reluctant to produce smaller and more compact components. Modularization efforts by portable computer vendors are mostly restricted to very limited extent, such as CPU modules, memory modules, internal modems, etc. Lack of expandability plus severe price competition greatly reduces the chance for many new or existing technologies to be incorporated into portable computers. A lot of electronic components have to be designed as external modules. External modules are weak in the sense that they usually need separate power sources and can only communicate with a portable computer through slow I/O ports. Also handling external modules is cumbersome--a user must set up the external module every time when he/she needs to use it.
A new industrial standard--PCMCIA has been set up to establish a modular standard for portable computers. The PCMCIA card is a credit card size module with a standard connector in its front end which can be slid in a card slot of a portable computer almost like a 3.5" floppy diskette. The PCMCIA card is very solid and portable which makes it a convenient solution for portable computer expandability. But it is not designed as a standard internal mounting mechanism for complete modularization of the portable computers. It is impossible to modularize a whole portable computer system based on PCMCIA card design.
New internal mounting mechanisms are necessary to allow complete modularization of portable computers to accommodate new technologies and changes, and also to avoid all the drawbacks from traditional screw mounting mechanisms and other problems discussed above.
Modular assembly and enclosure design of electronic devices and computer systems is the subject matter disclosed in several U.S. patents.
U.S. Pat. No. 4,748,540 to Henneberg et al., entitled "Compact Packaging of Electronic Equipment within Small Profile Enclosure" (May 31, 1988) discloses a computer enclosure system having a plurality of modular shelves mounted on a pair of rail members attached to the rear of the enclosure. It also includes cable troughs and enclosure openings to improve cable connection arrangements and air flow efficiency. The modular packaging disclosed in this patent may provide a means to improve the inter-connection of the cables between the shelves and provide a more compact and lower profile computer system. However the internal mounting mechanism presented by Henneberg is too complex and difficult to be implemented in a small, low-profile portable computer system.
U.S. Pat. No. 4,728,160 to Mondor et al., entitled "Cabinet for a Computer Assembly" (Mar. 1, 1988), discloses a computer system housing having a frame base to support a main unit comprising a central processor and a power supply. The computer system also has a front compartment for mounting the mass storage memory units. The frame and the housing are designed to provide easy access for removal, repair, or replacement. Again, the internal mounting mechanism presented in this patent is also too complex and difficult to be implemented in a portable computer system.
Leitermann et al discloses in U.S. Pat. No. 4,934,764, entitled "Computer System Module Assembly", (Jun. 19, 1990) a multi-level frame structure wherein each level is a horizontal module having an enclosure which houses a plurality of computer components. Some of the electronic components are configured to be inserted by sliding into the horizontal module and clamped to the module structure. The horizontal modules are then further assembled into a stack by the use of a modular exoskeletal frame structure which provides a means to securely engage the horizontal modules. Similar to the Mondor patent, the horizontal modules disclosed in this patent provide easy access for repair, removal, and replacement. However, the internal mounting mechanism is not suitable for a portable computer.
In general, all the prior art devices fail to solve the internal mounting problems of portable computers where the mounting mechanisms are very complex and impose a high level of difficulty to modify existing designs.